BirdAnalyst
Species · Colorado · BBS 2026 Release · 1966–2025

American Dipper Population Trend in Colorado

All statesWetland birds

American Dipper in Colorado has fallen sharply: down 54% on the route-weighted index since 1976.

-54%Since 1976TrendPercent change in the route-weighted abundance index between a smoothed baseline window and the most recent one. It tracks direction, not absolute population.Full methodology →
38Routes In StateSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
49YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable American Dipper Trends in ColoradoNotable signalsLong-arc shifts the engine flags automatically — sustained declines or increases large enough to stand out from year-to-year noise.Full methodology →

long arc declinecomputed indexTrend sourceWhether the figure is our own computed route-weighted index or an official USGS modeled estimate. The current build labels every trend as computed.Full methodology →

American Dipper has fallen sharply in Colorado: down 54% on the route-weighted index since 1976.

American Dipper Population Forecast in Colorado

If the recent trend holds, American Dipper in Colorado is projected to stay roughly flat through 2030, near 0.02 (95% range 0.00–0.15). A 5-year backtest shows a typical error of ±36.5%, with 100% of held-out values landing inside the 95% band.

n/aChange by 2030TrendPercent change in the route-weighted abundance index between a smoothed baseline window and the most recent one. It tracks direction, not absolute population.Full methodology →
0.02Projected 2030 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–0.1595% range95% rangeThe 95% uncertainty band around the projection at the forecast horizon. The true value should land inside it most of the time.Full methodology →
±36.5%Backtest errorBacktest errorTypical error when we hold out the most recent years, forecast them, and compare to what actually happened. Lower means a more trustworthy projection.Full methodology →
If the recent trend holds, American Dipper in Colorado is projected to stay roughly flat through 2030, near 0.02 (95% range 0.00–0.15). A 5-year backtest shows a typical error of ±36.5%, with 100% of held-out values landing inside the 95% band.19722030
Projection of the recent trend (dashed) with 80/95% bands — a projection, not a prediction. Habitat, climate, and land use are not modeled.
YearProjected indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →95% low95% rangeThe 95% uncertainty band around the projection at the forecast horizon. The true value should land inside it most of the time.Full methodology →95% high95% rangeThe 95% uncertainty band around the projection at the forecast horizon. The true value should land inside it most of the time.Full methodology →
20260.030.000.16
20270.030.000.16
20280.030.000.15
20290.030.000.15
20300.020.000.15

American Dipper Survey Routes in Colorado

Routes recording American Dipper in Colorado.
Recent countThe raw number of individuals recorded on this route in its most recent survey year. A single-route tally, not a trend.Full methodology →
Guanella Pas420242016
Tincup420181992
Buford220172017
Aspen220131979
Lost Lake220121993
Tarryall220091991
Dolores Riv220051991
Lake City219971988
Fox Creek220241997
Harmony120171979
Trail Ridge Road120062003
Cheesman Lk120221975
Delta119981985
Colona119881976
Parlin120221977
Pagosa Spgs119721972
Rio Grnds Rs120092009
Red Cliff120171989
Castleton120172015
Comanche Pk120142000
Ragged Mtn.119991999
Weston Pass120001994
Powderhorn120251994
Marshall Pas120112011
South Fork120111999

American Dipper Population Trend in Other States

alaskacaliforniaidahomontananevadanew-mexicooregonsouth-dakotautahwashingtonwyoming

Source: USGS North American Breeding Bird Survey, retrieved 2026-08-14.